See the glossary definition of Base Document
  1. Click on the comparison for which you want to change the base document
  2. Click on Heatmap
    • A witness list containing the documents you chose will appear on the left, and the current base document will appear on the right
  3. In the witness list, click on the title of the document you want to be the base document
    • The document will be highlighted in blue, and that document will appear in the right window